Traffic signal system



@CZC. 4, 15 232. c, WHETNEY 1,88%618 TRAFFIC S IGNAL SYSTEM Filed Nov.19, 1928 Inverter Chaney F1 \Whitnag. O3

Patented Oct. 4, 1932 UNITED STATS PAENT OFFICE CHANCY r. WHITNEY, orSCOTIA, new YORK, ASSIGNOR ro GENERAL ELECTRIC COMPANY, A CORPORATION orNEW YORK TRAFFIC SIGNAL SYSTEM Application filed November 19, 1928.Serial No. 820,247.

erated in response to sound produced on vehicles.

Means are now known whereby traflic signals which are utilized at theintersection of a main street and a side street may be adjusted normallyto produce safe signals on the main street and danger signals on theside street and controlled in response to the sound'of the horn on avehicle on the side street, the operator of which wishes to gainadmission to the main street. In response to the sound of the horn thesignals are operated through the usual cycle of operations including asafe signal to traflic on the side street and a danger signal to trailicon the main street and are then returned to the normal condition of safeon the main street and danger on the side street.

In systems of this kind it is necessary that means be provided wherebywhen the cycle of operations has once been started it cannot beinterfered with by subsequent sounding of horns on the side street untilthe signals have returned to the normal condition and a safe signal onthe main streetand a danger signal on the side street have beenmaintained for a predetermined period of time. It is also desirable thata signal be given to the vehicle operator who has sounded his hornduring this predetermined period of time thereby to gain admission tothe main street to inform him that the equipment has responded to the Isound of his horn and that the signals will change after thispredetermined period'has terminated.

One of the objects of my invention is to provide means whereby theseresults may be accomplished which are of more simple construction and ofmore reliable operation than systems of known form, Another object ofthe invention is to provide means whereby the warning signal which iscommonly used to indicate that a change in signals is about to occur mayalso be utilized as'an indication to the operator that the sound of hishorn has been registered by the equipment and that the lights willchange after a predetermined time interval.

Still another object of the invention is to provide means whereby thetraflic signals may be operated not only in response to sound producedby vehicles on the side street but whereby the signals may also beoperated by pedestrians who desire to cross the main street.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. y organizationand method of operation, tonether with further objects and advantagesthereof may best be understood by reference to the following descriptiontaken in connection with the accompanying drawing in which the singlefigure represents an embodiment of my invention. 7

Referring to the drawing 1 and 2 represent respectively the'signalhousings which are mounted upon the main and side streets in the usualmanner. Each of these housings includes a danger signal R, a cautionsignal A, and a safe signal G, these letters being indicative of thecolors red, amber and green which are commonly employed.

In accordance with the system to be disclosed these signals arecontrolled by means of a timing mechanism or controller 3 which is ofwell known construction, such as, for example, that shown in Patent N 0.1,851,246, granted March 29, 1932 to Chester I. Hall, and this timingmechanism is in turn controlled responsively to sound produced uponvehicles upon the side street. The means invention itself, however, bothas to its whereby this result is accomplished comprise 1y energized froman alternating current supply circuit 10 to which they are connectedthrough conductors 11 and 12. The disk 8 serves'to drive the shaft 13 ina counterclockwise direction through a chain of gears 14. The shaft 13carries a plurality of cams 15, 16, 17 18 and 19 which cams are arrangedin spaced relation withrespect to each other and cooperate with levers20 and 21 to control the position of a non-conducting member 22. Thismember 22 serves to operate contact fingers 23, 24, 25 and 26, whichfingersin turn control the position of the signal lamps R, A and G. Eachof these contact fingers cooperate with a stationary contact, all ofwhich are connected together and to one side of the supply circuit 10through conductors 27 and 28. v y

With the induction disk motor 8, 9 in the position shown in the drawing,it will be seen that contact finger 25 only is in engagement with itsstationary contact. A circuit is completed which extends from one sideof the supply circuit 10 through conductor 28, contact finger 25,conductor 29, lamps G on the main street and R on the side street, andconductor 30 to the opposite side of the supply circuit. Thus normallythe lamp G provides asafe signal upon the main street and the lamp R adanger signal upon the side street. The motor 8, 9 is normallyrestrained in this position by means of a brake magnet 31. Brake magnet31 has an armature 32 which swings about a. pivot 33 and which carriesnear its outer end a lever 34. The lever 34 swings about a pivot 35 andis arranged such that when the magnet 31 is energized, a projecting foot36 on the lever 34 engages the disk 8 and the opposite end of the lever34 falls within the path of travel of a stud 37 mounted upon a cam 38which is carried by the shaft 13. Normally the stud 37 is in engagementwith the lever 34 and bearing down thereon presses the foot 36 intoengagement with disk 8 thereby restraining the disk and shaft 13 againstrotation. This brake magnet 31 is energized through a circuit whichextends from one side of the supply circuit 10 through conductor 11,actuating winding of the brake magnet 31, upper stationary contact andarmature of relay 7 to theopposite side of the supply circuit 10. Relay7 is normally connected across the supply circuit 10 through thearmature and upper stationary contact of relay 6, which relay isincluded in the anode circuit of an electron discharge device 5.

The electron discharge device 5 is of the usual three-element typehaving a condenser and grid-leak. combination 39 connected in the gridcircuit thereof, in series with the secondary winding of a microphonetransformer 40. The primary winding of this transformer is included incircuit with a smoothing condenser 41 and the microphones 4. A

direct current potential is impressed upon supply circuit and thesecondary 43 of which supplies potential through'a rectifying unit 45 tothe condenser 41. This rectifying unit may be of any suitable form butpreferably is comprised of rectifiers of the type shown in United StatesPatent No. 1,640,335 to Lewis 0. Grondahl issued August 23, 1927. Theanode circuit of the electron discharge device 10 extends from the upperside of the supply circuit 10 through the space between the cathode andanode of electron discharge device 5, winding of relay 6, armature andupper contact of relay 6 to the opposite side of the supply circuit.

With the apparatus in the position shown in the drawing, let us assumethat an operator, desiring to gain admission from the side street to themain street, sounds his horn. The microphones 4 operate and in a wellknown manner act upon the grid of the device 5 to diminish the currentflowing in the anode circuit of that device. Relay 6 is deenergized andits armature is actuated into engagement with its lower contact therebyinterrupting the anode circuit of device 5- and deenergizing relay 7.The armature of relay 7 is then actuated to its lower position therebydeenergizing the brake magnet 31, which in turn releases its armatureand thereby permits themotor 8, 9 todrive the cam shaft 13 in acounterclockwise direction. "At the same time the armature of relay 7completes an indicating circuit which extends from one side of thesupply circuit 10 through the armature and lower contact of relay 7,conductor 46, signal lamp A in the housing 2 on the side street andconductor 30 to the opposite side of the supply circuit 10. The lightingof the signal lamp A indicates to the operator that his signal has beenregistered, and that after a predetermined interval of time the signalswill change.

Upon rotation of the shaft 13through apre; determined are it will beseen that the lever 21 which rides upon cam 17 will drop down upon cam19 and in so doing the member 22 carried by the lever 21 will be movedforward. This movement will be suflicient to,

at this time since this lamp is already lighted.

Upon further'rotation of the shaft 13 the lever 21 will drop from cam 19on to cam 18 and'thereby move member 22 a second step forward. In thisposition contact finger 26 will be actuated into engagement with itsFinger stationary contact and will thereby cause the energization of thedanger lamp R on the main street and the safe lamp G on the side street.-At the same time this finger will again complete the anode circuit ofdischarge device 5 and energize relay 6. This circuit extends from oneside of the supply circuit 10 through conductor 28, finger 26, lowerstationary contact and armature of relay 6, act-uating winding of relay(3, anode and cathode of electron discharge device 5 to the otherside'of the circuit 10. Relay 6 will now again be energized and willactuate its armature to the normal position thereby again energizingrelay 7 which in turn actuates its armature to the normal position. Inthis position these relays are maintained energized through the armatureand upper contact of relay 6. Brake magnet 31 is now again energized andactuates its armature 32 and lever 34 to the position shown in thedrawing. However, since the stud 37 is not now in the position shown inthe drawing the foot 36 of lever 34 will be held away from disk 8 byspring 50 and, hence, will not stop the rotation of the disk. lVith thecontroller in this position contact fingers 23 and 21 are both moved outfrom engagement with their sta tionary contacts, and, accordingly, thecaution signals A on both the main and the side streets areextinguished.

The lever 20 which is now riding upon cam 16 will, after a furtherrotation of the shaft 16, drop down upon the portion 48 of cam 15. Uponthis movement the upper end of lever 20 will engage lever 21 and therebyoperate the member 22 into the position where caution signals weregiven. In this position fingers 23 and 24; are in engagement with theirstationary contacts, and thereby energize the caution signals, whilefingers 25 and 26 are both out from engagement with their stationarycontacts. hen the period for caution signals has terminated the lever 20will drop from the portion 48 of the cam 15 on to the portion 49 of thatcam. and w ll thereby operate the member 22 back to the position shownin the drawing, thereby extinguishing the caution signals and againlighting the safe signals on the main street and the danger signals onthe side street. After these signals have been maintained forapredetermined interval of time the stud 37 will again engage the end ofshaft 34. Since the magnet 31 is now energized the lever 3 will fulcrumabout the point 35. and thereby bring pressure upon the disk 8sufficient to stop the motor. The signals will then be maintained inthis position until the microphones et again respond to sound producedupon a vehicle.

It will be seen that after the motor 8, 9 has been released bydeenergizing the brake magnet 31 in response to sound, the foregoingcycle of operations will ensue and that no of device 5.

interference can result from any subsequent sounding of horns upon theside street. During the cycle of operations the period of each of thedifferent signals is determined entirely by the controller. the mainstreet and the danger signal on the side street have been restored thecontroller is stopped by engagement of stud 37 with the lever 31 andthese signals are maintained until subsequent actuation of thecontroller in response to sound produced on the side street. If, priorto this engagement one of the micro phones 1 is actuated, it will beseen that the caution light A on the side street will be lit'htedinforming the vehicle operator that the sound of his horn has beenregistered. The magnet 31 will also be deenergized but the safe signalwill be continued for the predetermined interval which is determinedentirely by the controller. lVhen this interval is terminated. due tothe fact that the magnet 31 is deenergized, the stud 37 will not engagethe member 31, and, accordingly, another revolution of the shaft 13 willfollow, thereby causing a subsequent cycle of operations.

To provide means whereby pedestrians upon the side street may obtain theright of way to cross the main street a key 51 is inserted in themicrophone circuit. This key will preferably be mounted in convenientreach of the 1 edestrian at the street corner, and if desired one keymay be provided at each corner and all arranged to interrupt or vary thecurrent in the microphone circuit. hen the pedestrian opens the contactsof key 51 the current in the microphone circuitis interrupted therebyproducing, through transformer 10, a voltage impulse upon the grid Thisimpulse will cause the above cycle of operations to ensue.

lVhile have mentioned the use of my invention particularly in theoperation of traftic signals at street intersections it will of coursebe understood that it has utility in other fields, as, for example. inrailway signaling. Further. while I have described a particular cycle ofoperations. it will be understood that this cycle of operations, isdedetermin'ed entirely by the controller and may be varied as desired.

IVhile I have shown a particular embodiment of my invention, it will ofcourse be understood that I do not wish to be limited thereto since manymodifications. both in the circuit arrangement and in theinstrumentalities employed, may be made without departing from thespirit and scope of my invention, as set forth in the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In a signal system for intersections of main and side streets,comprising a danger signal on the main street and safe and dangersignals on the side street, a controller arranged for rotation, meanstending to rotate lVhen the safe signal on Ill] ' troller and forinterrupting said anode circuit, connections between said controller andsaid signals, whereby after said controller is released the signals onthe side street are changed from danger to safe and then to danger, andsaid danger signal on the main street is operated simultaneously withthe safe signal on the side street and means responsive to operation ofthe controller to a predetermined position for completing said anodecircuit thereby to restore said relay and brake magnet to the normalcondition.

2. In a signal system for main and side street intersections, comprisinga danger signal on the main street and safe, danger and caution signalson the side street, a relay having normally closed and normally opencontacts and an energizing circuit, means responsive to sound producedon the side street to interrupt said energizing circuit, a circuit forsaid caution signal including said normally open contacts, a controllerarranged for rotation, means for restraining said controller in apredetermined position against rotation, said means including a magnethaving a holding circuit including said normally closed contacts,whereby in response to said sound on said side street said cautionsignal is energized through said normally open contacts and said magnetis deenergized, connectlons between said controller and said signalswhereby said caution, safe and danger signals are operated through apredetermined cycle of operations when said controller is released, andmeans responsive to operation of the controller to a predeterminedposition to complete said energizing circuit of said relay and therebycause deenergization of said caution signal and energization of saidmagnet.

53. In a signal system for main and side street intersections,comprising a danger signal on the main street and safe and dangersignals on the side street, an electron discharge device, a relay havinga Winding and contacts included in said anode circuit, means includingsaid electron discharge device whereby sound produced on the side streetis caused to operate said relay thereby to interrupt said anode circuit,a controllerarranged for rotation, means for restraining said controller in a predetermined position against rotation, said meansincluding a magnet, a second relay, means to control said second relayin accordance with the operation of said first relay, said second relayhaving contacts ing said contacts whereby said controller is releasedupon operation of said second relay,

connections between said controller and said signals whereby when saidcontroller is released said signals are operated through a cycle ofoperations, means including said first relay responsive to operation ofsaid controller to a predetermined position for again completing saidanode circuit whereby said first relay is energized and said secondrelay is operated to restore said magnet to the initial condition.

4. In a signal system for main and side street intersections, comprisinga danger signal on the main street and safe, danger, and caution signalson the side street, an electron discharge device, a relay having awinding and contacts included in said anode circuit, means includingsaid electron discharge device whereby sound produced on the side streetis caused to operate said relay, thereby to interrupt said anodecircuit, a controller arranged for rotation, means for restraining saidcontroller in a predetermined position against rotation, said meansincluding a magnet, a second relay, means comprising connections tocontrol said second relay in accordance with the operation of said firstrelay, said second relay having contacts in circuit with said cautionsignal and said magnet, means comprising said contacts whereby saidcontroller is released upon operation of said second relay, and saidcaution si nal is simul-- taneously energized, connections between saidcontroller and said signals whereby when said controller is releasedsaid signals are operated through a predetermined cycle of operations,means including said first relay responsive to operation of saidcontroller to a predetermined position for again completing said anodecircuit whereby said first relay is energized and said second relay isoperated to restore said magnet to the initial condition and saidcaution signal is deenergized.

In witness whereof I have hereunto set my hand this 17th day ofNovember, 1928.

CHANGY F. WHITNEY.

